Emergency-stop for electrically-driven apparatus.



C. D. SWETL EMERGENCY STOP FOR ELECTRICALLY DRIVEN APPARATUS.

APPLICATION FILED APR. 5, i916.

Patented Dec. 18,1917,

2 SHEETSSHEET IN VENTOR c; n. swm.

EMERGENCY STOP FOR ELECTRFCALLY DRIVEN APPARATUS 1,250,708.

APPLHZATEOH FILiD Aim. 5 11935.

* Patented Dec. 18,1917.

2 SHEETS-SHEET 2.

WITNESSES:

- UNITED STATES PATENT OFFIGE.

GASWELL D. SWETT, OF REDWOOD CITY, CALIFORNIA.

EMERGENCY-STOP FOR ELECTRICALLY-DRIVEN APPARATUS.

Application filed April 5, 1916.

To all whom it may concern:

Be it known that I, CAswELL D. SWETT, a'citiz-en of the UnitedStates, residing'at RedwoodCity, in the county of San Mateo and State of California, have invented new and useful Improvements in Emergency Stops for Electrically-Driven Apparatus, of which the following is a specification.

This invention relates to emergency stops for electrically driven devices and has for its object to simplify and improve the construction and operation of a device of the character shownand described in my prior application, Serial No. 843,466, filed June 6, 1914, entitled Automatic safety stop for line shafts.

In carrying out this object I employ in combination with an electric motor and an element driven thereby, a switch for changing the pole connections of the motor, where by to reverse the torque of the latter to therebyhasten the stoppage of the driven element, said switch being of an improved and simplified form and having an electro magnetic device to retain it in position for closing the forward driving circuit of the motor, said electro-magnetic device being adapted to be operated from various and remote points to release the switch, means for moving the switch to position where the reverse driving circuit of the motor is closed, and rotatable means adapted to be connected to the driven element and which on thereversal thereof acts to move the switch to neutral position whereby to break the operating circuits of the motor, all of said parts being compactly arranged and mounted within or upon a casing for convenience in installing.

One form which my invention may assume isexemplified in the following description and illustrated in the accompanying drawings in which- Figure 1 shows a plan view of a device embodying my invention.

Fig. 2 shows a longitudinal central sectional view of the electro-magnetic latch device employed therein.

Fig. 3 shows a detailed view partly in section, of one of the conducting elements of the switch.

Fig.4 shows a detailed sectional view of the crank arm of the switch.

Fig. 5 shows a. side elevation of the device shown in Fig. 1.

Specification of Letters Patent.

Patented Dec. 18, 1917.

Serial No. 89,060.

Fig. 6 shows a sectional view taken on line 66 of Fig. 2.

Figs. 7 and 8 show detailed sectionalviews of the pulley wheel and ratchet clutch employed in the device.

Fig. 9 shows a diagram of the electrical connections.

In the particular form illustrated I have shown a casing 10 having the shape of a quadrant and arranged to contain the pole changing switch, which latter has a plurality of conducting arms 11 carried on a shaft 12 and insulated therefrom, the shaft being journaled in the casing. At the outer ends of the conducting arms 11 are oppositely disposed contact points 13 preferably of carbon and adapted to contact at one end of movement of the arms with stationary terminals 14 of suitable conducting material preferably carbon, which are connected to the forward driving circuit of the motor, and at the other end of movement of said arms with stationary terminals 15 also of carbon which are connected to the reverse driving circuit of the motor. The pivoted members 11 have their inner ends provided with arcuate metallic brushes 16 incontinuous contact with stationary arcuate terminals 17, which latter have their bases 18 mounted upon insulating material 19 attached to. the side of the casing and carry binding posts 20 adapted to be connected to thewires leading from the source of current.

Each stationary switch point 1 and 15 is carried in a holder 21 insulated from the casing by blocks 22 of suitable non-conducting material and each has a binding post 23 for attachment to the feed wires running to the motor.

Fixed to the outer end of the shaft 12, outside of the casing, is a crank arm 24 with which cooperates the plunger 25 of a solenoid magnet 26, the latter secured to the adjacent side of the casing. The plunger is adapted to enter an opening 27 in the crank arm to retain the switch in closed position where the motor will be driven forward. A torsion spring 28 is arranged between the crank arm and casing and tends to turn the shaft 12 in a direction for moving the switch arms 11 into contacting position with the terminals 15 for closing the reverse circuit to the motor.

Near one corner of the casing is a shaft 29 .journaled in a bearing 30 and carrying a pulley wheel 31 loosely thereon, which pulley wheel is adapted to be connected by a belt or otherwise to the driven element operated by the motor. A tightener 32 is shown for the belt. Fixed upon the shaft 30 is a crank arm 33, having a cam surface to co-act with the cam surface on an arm 34 of a bell-crank 35 journaled on the casing and carrying on its opposite end a roller 36 to cooperate with the crank arm 24L of the switch when the latter is in position for closing the reverse circuit. A tor sion spring 37 acts to retain the bell-crank normally in position to permit the crank arm 2% to move to position where the switch arms 11 may contact with the terminals 15; a lug 38 on the casing serving to limitthe retracted movement of the bell-crank. A ratchet-wheel 39 is fixed to the shaft 30 within the pulley-wheel 31 and a pawl 40 cooperating therewith is carried by said pulley wheel so that the shaft 29 is driven in but one direction and only when the element operated by the motor is reversely turned.

The electrical connections contemplate mains A and I3, each running to a post 20 of the switch, feed wires C and D connecting each with a post 23 of the switch and running to the pole pieces E and F respectively of a motor a lVith the switch arms 11 in contact with the points 14, a circuit will be closed through the motor for driving it in a forward direction. Feed Wires G and H connect each to a switch point 15 and extend to the poles F and E of the motor, respectively, and thus when the switch arms 11 contact with the points 15, a circuit is established through the motor, which will operate the motor in a direction opposite to the former circuit.

The solenoid magnet has a separate circuit I and J, shown as connected to one of the mains AB and to a third main K of a three wire distribution system, and in this circuit are a plurality of push-buttons 42 for closing the circuit from various and remote points whereby to excite the magnet and withdraw the plunger 25 to thereby release the crank arm and allow the switch to change its position.

In the operation of the device with the pole changing switch connected to the motor in the manner described, the switch arms 11 are manually placed in contactin position with the terminals of the forward driving circuit and held there by means of the plunger 25. The pulley-wheel 81 is connected by a belt or otherwise to a convenient rotatable member driven by the motor i1. Should an accident occur, which would necessitate the instant stopping of the driven machinery, an operator or attendant pushes a con venient push button 42, thereby releasing the crank arm 2%, whereupon the spring throws the switch arms 11 into contacting position with the opposite terminals, thus changing the direction of current through the motor and reversing the torque thereof. This reversal of current operates to hasten the stoppage of the motor and similarly the reversal of torque of the motor acts to hasten the stoppage of the driven element. Immediately following the stoppage of the driven element and coincident with the initial reverse movement thereof, the pulleywheel 31 will be operated in a direction to turn the shaft 29 through the ratchet clutch mechanism. The cam arm 83 on the shaft will, at this time, engage with the bell-crank, moving the latter in a direction to throw out the switch and retain it in neutral position as shown in dotted lines in Fig. l, and thus reverse movement of the motor beyond what is required to stop the driven element is prevented. Manual or other means may be used to restore the switch to position for closing the forward driving circuit.

In practice the switch box or casing is provided with clips or legs i3, for mounting the same in place and inasmuch as all parts or" th device are carried within, or upon, the casing, the installation is greatly simplified.

I have shown the switch as being provided with three points at each terminal by means of which the switch can be used with a three wire system of distribution, if desired.

Various changes in the construction and arrangement of the several parts herein shown and described may be employed without de arting from the spirit of my invention as disclosed in the appended claims.

The casing 10 is made oil-tight and, in practice, is filled with transmission oil for insulating purposes.

Having thus described my invention, what I claim and desire to secure by Letters Patent is- 1. In an emergency stop for electrically driven apparatus, the combination with an electric motor and an element driven thereby, of a pole changing switch for the motor circuit spring-pressed to position for closing the circuit in the reverse direction, means for retaining the switch in position for closing the forward driving circuit, electrically operated means for releasing the switch to permit it to move to position for reversing the circuit, and means actuated by the initial reverse movement of the driven element for moving said switch to neutral. position.

9. In an emergency stop for electrically driven apparatus, the combination with an electric motor and an element driven thereby, of a pole changing switch for the motor circuit, an electro-magnet for controlling the reversal of the switch, means actuated by the initial reverse movement of the driven element for moving said switch to neutral position and a plurality of controlling devices, for .the electro-magnet located at various and distant points.

3. In an emergency stop for electrically driven apparatus, the combination with an electric motor and an element driven thereby, of a pole changing switch for the motor circuit, means for reversing the position of the switch, means actuated by the initial reverse movement of the driven element for moving said switch to neutral position, and a casing for said switch forming also a stand for the last mentioned means.

4:. In an emergency stop for electrically driven apparatus, the combination with an electric motor and an element driven thereby, of a pole changing switch for the motor circuit, means for reversing the position of the switch, and means for moving said switch to neutral position upon the initial reverse movement of the driven element, said means comprising a throw-out member for the switch and a rotatable member clutched to the driven element for movement in a reverse direction for actuating said throw-out member.

5. In an emergency stop for electrically driven apparatus, the combination with an electric motor and an element driven thereby, of a pole changing switch for the motor circuit, said switch comprising a spring actuated conducting member normally impelled in a direction to close the reverse circuit, releasable means for retaining the member in retracted position where the forward driving circuit will be closed and a throw-out member actuated by the initial reverse movement of the driven element for moving said member to break the reverse circuit.

6. In an emergency stop for electrically driven apparatus, the combination with an electric motor and an element driven thereby, of a pole changing switch for the motor circuit, said switch comprising a spring actuated conducting member normally impelled in a direction to close the reverse circuit, releasable means for retaining the member in retracted position where the forward driving circuit will be closed, a throwout member actuated by the initial reverse movement of the driven element for moving said member to break the reverse circuit and a rotatable cam clutched with the driven element for movement in a reverse direction to actuate said throw-out member.

7. In an emergency stop for electrically driven apparatus, the combination with an electric motor and an element driven thereby, of a pole changing switch for the motor circuit, said switch comprising a spring actuated conducting member normally im pelled in a direction to close the reverse circuit, releasable means for retaining the member in retracted position where the for ward driving circuit will be closed. a throwout member actuated by the initial reverse movement of the driven element for moving said member to break the reverse circuit, a shaft, an arm on said shaft for actuating the throw-out member, a rotatable member loose on said shaft and adapted to be connected to the driven element for continuous operation and a ratchet clutch between the shaft and rotatable member forming a driving connection when the rotatable member is reversely driven, whereby to move said arm to position for actuating the throw-out member.

8. In an emergency stop for electrically driven apparatus, the combination with an electric motor and an element driven thereby, of a pole changing switch for the motor circuit, said switch comprising a casing, a shaft journaled in the casing, conducting arms on the shaft connected to the supply mains, terminal members at either end of moven'ient of the arms connected respectively to the forward and reverse operating circuits for the motor, a crank arm on the shaft exterior of the casing, a spring on the shaft for moving the conducting arms into contacting position with the reverse circuit terminals and disengageable means on the exterior of the casing cooperating with said crank-arm for retaining the conducting arms in contact with the forward circuit terminals.

9. In an emergency stop for electrically driven apparatus, the combination with an electric motor and an element driven thereby, of a pole changing switch for the motor circuit, said switch comprising a casing, a shaft journaled in the casing, conducting arms on the shaft connected to the supply mains, terminal members at either end of movement of the arms connected respectively to the forward and reverse operating circuits for the motor, a crank arm on the shaft exterior of the casing, a spring on the shaft for moving the conducting arms into contacting position with the reverse circuit terminals and releasable means on the exterior of the casing cooperating with said crank-arm for retaining the conducting arms in contact with the forward circuit terminals, said means comprising a solenoid magnet having its plunger arranged to engage with th crank arm.

10. In an emergency stop for electrically driven apparatus, the combination with an electric motor and an element driven thereby, of a pole changing switch for the motor circuit, said switch comprising a casing, a shaft journaled in the casing, conducting arms on the shaft connected to the supply mains, terminal members at either end of movement of the arms connected respectively to the forward and reverse operating circuits for the motor, a crank arm on the shaft exterior of the casing, a spring on the shaft for moving the conducting arms into contacting position with the reverse circuit terminals, releasable means on the exterior of the casing coopcrating with said crankarm for retaining the conducting arms in contact with the forward circuit terminals and a throw-out device on the casing cooperating with said crank arm to move the conducting arms out of contacting position with the reverse circuit terminals said throw-out device being connected to the electrically driven apparatus and operated upon the initial reverse movement thereof.

11. In an emergency stop for electrically driven apparatus the combination with an electric motor and an element driven therey, of a pole changing switch for the motor circuit, said switch comprising a casing, a shaft journaled in the casing, conducting arms on the shaft connected to the supply mains, terminal members at either end of movement of the arms connected respectively to the forward and reverse operating circuits for the motor, a crank arm on the shaft exterior of the casing, a spring on the shaft for moving the conducting arms into contacting position with the reverse circuit terminals, means on the exterior of the casing cooperating with said crank-arm for retaining the conducting arms in contact with the forward circuit terminals, a bell-crank journaled on the casing and cooperating with the crank arm to move the conducting arms out of contacting position with the reverse circuit terminals; a shaft -journaled on the exterior of the casing; an arm on said shaft to actuate the hell-crank and a one-war driving connection between the shaft and the driven element.

In testimony whereof I have hereunto set my hand in the presence of two sul')scribing witnesses.

GASWELL D. SVVETT.

WVitnesses JOHN H. HERRING,

*V. N. HEALEY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. C. 

